Three-dimensional printer



FIG. 1 is a front perspective view of a three-dimensional printer showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a side elevational view thereof. The opposite side is a mirror image.

The broken lines are for purposes of illustration only and form no part of the claimed design. 

The ornamental design for a three-dimensional printer, as shown and described. 